Piston



w. H. sAcKMAN.

PISTON.

- APPLICATION FILED APR. IZ, 1919. I I 1 ,42 6,9 1 3. Patented Aug. 22, 1922.

f, `Z7 P Z rze i ythis groove, and the i supporting'.bossesy 11, 121and set screw `openy ingl ef retention he piston beyond the bosses is contracted I at lei to provide for a circumferential seat 15 occupied by arpreferably cast iron insert 16 in the forni of a ring-supporting shell or banrlvgrooved `at 17, 17', 172 for packing rings, not shown. The closed end 18 and the contracted end portion Iare reinforced by ribs 19. y t

The edge'20 ofthe groove 172 is chainered forfthe lpurpose of providing a cir- `cumferentially-eXtending oil' groove adjoining the rearedge ofthe ringfitting within groove is connected with ind'er` by means of openthezinterior. of the cy ings 21, so thatthe oil scoured from the interior.o'1`i.the vc ylinderon the back stroke ofl the piston is `ed `into the interior of the pistonthrough Athese openings. These opengings may extend `at anyy convenient angle,

shownzasvariant in Figures 3 and 16.

1I have found that the shell or band 1nse-rt 16 is best retained'in rigid position with- 'inrthe piston by preliminarily forming 'the shell oriband, centering it within the mold forlthepiston as well as possibley and casting thebo'dy 'of the pistonabout it. The castbody kmaterial*and the shell or band are in` terfitted by providing holes 22l in the ring shell *or band, counter-sunklat- 23, within which Ythe molten body metal flows. These holes are preferably radial, ilike spokes 234;, andare shown as terminating in the grooves *517,1'17 17?', asdistinguished l'rom terininatingvwithin the intermediate ribs 25. These ribs thus retainltheir full strength, both for sti'ness and for wear. i

The insert 16 is heated before being placed in the mold but is givenat least a linish cut after the Casting to ensure alinement.

Though the metal of the body of the piston has a higher coeiicientlof expansion than the @cast ,iron and, being hotter when it is poured than the heated ring-earring shell or band, shrinks slightly away from it, it will 'of 'the groove within which they lie.

be obvi'ous that the diameters of the pins are so small'4 that `the'difference in shrinkage between the pins and the surrounding winetal of the liolesinthe shell or band willb'e sliglit and an effective tight engagement between the 'pinswand the adjoining' side walls wil'ljbe 'maintained such as could not be obtained between `the `insert land theend walls In practicei'the l`'pin ylengagernent satisfactorily prevents rattling even when cold .and much moreeffec'tive'for this purpose at the temn wint@ evidenti aai, the pin form @fia ter-connection between the interior1 material of the piston and the Y'surrounding ringcarrying .shell or band gives strongsrpokelike 'contact and that theptapering of the pins adds to the strength ofthe pins against bendingstrain as well as Agreatly increasing l ktheir resistance against shearing.

Iny order to stiffen the piston and tov reinforce it at'its rear end againstvwear, I have restricted the piston bodyat 26, to ioi'in a seat 27 within which a cast iron Vor steel collar v28 as inserted.

The collar v,may be placedin position in'` Y Aing shell within the seat and interlockin,f``

.spoke-likeprojections'from a cylindricalsur'- 'p face ot' one of the parts,entering,the other at intervals aboutthe circumference.

2. ln a piston for engines .operated by eX'- i lplosive charges@ bodyfportion of light metal having a relatively high coeilicient of expant sion, interlocking spoke-like pins project-v ing from its cylindrical surface, at interlvals about the circumference, and anannu- Alar ring-carryingI shell of,1elatively lower coeiiicient of expansionxvengaged by said projections.

3. In a piston for engines operated by ,ex-

plosive chargefsa ring-carrying shell oftgenerally cylindrical form havinggrooves kfor a plurality otrings Mand apertures extending `,inwardly from the grooves and apiston body located partly within the shell and extend` ing into 4the apertures.'

l hln a piston y,for engines operated `by ext plosive charges, a ,ring support of generally 't cylindrical form having ia .plurality of4 grooves fori rings and aperturesextending inwardly fromthe grooves, enlarginginivardly and. aypiston body located. in Vpart within the support .and having projections fitting into the apertures. i

In a piston 4forengines operatedby fexplosive charges. a ring support having y radially-extending apertures growing ,larger in diameter as they extend inwardly, 1in

,combination with la piston bodyhaving pro,- iections kiittlI-liir :the apertures.v

y WILLIAM sAoKMAN. y 

